1. Field of the Invention
The present invention relates to a solid electrolytic condenser and method for manufacturing the same; and, more particularly, to a solid electrolytic condenser and method for manufacturing the same, in which a cathode drawing layer is formed on one side of a condenser element by a conductive paste, terminal reinforcements are adhered to bottom surfaces of the condenser element, so that it is possible to maximize volumetric efficiency of the condenser element, and ensure mechanical reliability of the product.
2. Description of the Related Art
In general, a solid electrolytic condenser is one of electronic components used for the purpose of breaking a direct current and allowing an alternating current to flow, in addition to the purpose of accumulating electricity. A tantalum condenser has been manufactured as a typical solid electrolytic condenser.
The tantalum condenser is used for industrial equipment and an application circuit which has low use range of a rated voltage. In particular, the tantalum condenser is mostly used for reducing noise of a portable communication device, or a circuit sensitive to frequency characteristics.
Such a solid electrolytic condenser is manufactured by inserting a lead wire into either a portion except for the center, or a center of a condenser element composed of tantalum, or by banding the inserted lead wire in outside of the condenser element.
Also, as a method for assembling a lead frame to the condenser element, there is used a method in which an anode terminal is drawn by spot-welding an anode lead wire and an anode lead frame, and an electrode terminal is drawn through an anode and cathode lead forming after performing mold package.
FIGS. 1 and 2 are views showing a conventional solid electrolytic condenser. FIG. 1 is a perspective view showing a conventional solid electrolytic condenser. FIG. 2 is a cross-sectional view showing a conventional solid electrolytic condenser.
As shown in drawings, the conventional solid electrolytic condenser 10 includes a condenser element 11 composed of a dielectric powder material which determines capacity and characteristics of the condenser, anode and cathode lead frames 13 and 14 connected to the condenser element 11 in such a manner to be easily mounted on a Printed Circuit Board (PCB), an epoxy case 15 which is molded with epoxy to protect the condenser element 11 from an external environment and makes a shape of the condenser element.
In this case, the condenser element 11 has a rod-shaped anode wire 12 formed on one side thereof to be protruded at a predetermined length.
The anode wire 12 has a pressurized air surface 12a which is provided with a flat external surface, so as to improve a rate at which it comes into contact with the anode lead frame 13 and to prevent right and left shaking at the time of welding.
Herein, a process for manufacturing the condenser element 11 includes a step of molding and sintering dielectric powder into a rectangular parallelepiped shape in a press process, a step of forming an oxidized film on an external surface thereof after undergoing a formation process, a step of impregnating the resulting oxidized film with manganese nitrate aqueous solution, and a step of performing thermal decomposition of manganese dioxide composed of solid electrolyte on the external surface thereof.
A process for connecting the anode lead frame 13 and the cathode lead frame 14 to the condenser element 11 manufactured in this manner includes a step of drawing an anode terminal by welding the plate-shaped anode lead frame 13 to the pressurized air surface 12a of the rod-shaped anode wire 12 protruded at a predetermined length on one side of the condenser element 11, and a step of drawing a cathode terminal via a conductive adhesive coated on either the external surface of the condenser element 11 or the cathode lead frame 14.
Then, the condenser element 11 electrically connected to each of the anode lead frame 13 and the cathode lead frame 14 is molded with an epoxy in an armoring process to form the epoxy case 15, and then a condenser is completely manufactured after finally performing a marking process.
In the conventional solid electrolytic condenser manufactured in this manner, as volumetric efficiency of the condenser element 11 becomes remarkably reduced from volume of entire solid electrolytic condenser including the epoxy case 15, capacitance is reduced, and impedance is increased.
Also, in the conventional solid electrolytic condenser, high temperature heat is generated during welding of the anode wire 12 and the anode lead frame 13, which results in the influence of the generate heat on the condenser element 11 through the anode wire 12. Therefore, the condenser element 11 vulnerable to heat is damaged.
As a result, the thermal impact applied to the condenser element 11 breaks dielectric, and thus characteristics of a product is deteriorated and a defective product is produced, resulting in a rise of the manufacturing costs.